The present invention relates to a method, apparatus, storage medium, and a program for processing information, and particularly to a method, apparatus, storage medium, and a program for processing information, that allow it to perform a more accurate evaluation of characteristics of a display.
Various kinds of display devices such as a LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), a DMD (Digital Micromirror Device) (trademark) are now widely used. To evaluate such display devices, a wide variety of methods of measuring characteristics such as luminance value and distribution, a response characteristic, etc., are known.
For example, in hold-type display devices such as a LCD, when a human user watches a moving object displayed on a display screen, that is, when the user watches an image of the object moving on the display screen, eyes of the human observer follow the displayed moving object (that is, the point of interest for the observer moves as the displayed object moves). This causes human eyes to perceive that there is a blur in the image of the object moving on the display screen.
To evaluate the amount of blur perceived by human eyes, it is known to take an image, using a camera, of the motion image displayed on the display device such that light from the image (motion image) displayed on the display device is reflected by a rotating mirror and reflected light is incident on the camera. That is, the image displayed on the display device is reflected in the rotating mirror and the image reflected in the rotating mirror is taken by the camera. In the process of taking the image using the camera, light emerged from the display device is reflected by the mirror and is incident on the camera. If the image is taken by the camera while rotating the mirror at a particular angular velocity, the resultant image taken by the camera is equivalent to an image obtained by taking the image displayed on the display screen while moving the camera with respect to the display screen of the display device. That is, the resultant image taken by the camera is equivalent to a single still image created by combining together a plurality of still images displayed on the display screen, and thus the resultant still image represents a blur perceived by human eyes. In this method, the camera is not directly moved, and thus a moving part (a driving part) for moving the camera is not required.
In another known technique to evaluate a blur due to motion, an image of a moving object displayed on a display screen is taken by a camera at a predetermined time intervals, and image data obtained by taking the image is superimposed by shifting the image data in the same direction as the direction of the movement of the object in synchronization with the movement of the moving object displayed on the display screen so that the resultant superimposed image represents a blur perceived by human eyes (see, for example, Japanese Unexamined Patent Application Publication No. 2001-204049).
However, in the technique in which a rotating mirror is used to obtain an image representing a blur perceived by human eyes, it is difficult to precisely adjust the position and the angle of the rotation axis about which the mirror is rotated, and thus it is difficult to rotate the mirror so as to precisely follow the movement of an object displayed on the screen of the display device. As a result, the resultant obtained image does not precisely represent a blur perceived by human eyes.
Besides, if the camera used to take an image of the display screen (more strictly, the camera used to take an image of an image displayed on the display screen) is set in a position in which the camera is laterally tilted about an axis normal to the screen of the display device under evaluation, the image taken by the camera has a tilt with respect to the display screen of the display device under evaluation by an amount equal to the tilt of the camera. To obtain a correct image, it is needed to precisely adjust the tilt. However, this needs a long time and a troublesome job.
Besides, in the conventional technique, characteristics of the display device are evaluated based on a change in total luminance or color of the display screen of the display under evaluation or based on a change in luminance or color among areas with a size greater than the size of one pixel of the display screen of the display device under evaluation, and thus it is difficult to precisely evaluate the characteristics of the display.